1-Year Clinical Outcomes Of High-Fluence Delayed Intrastromal Corneal Crosslinking For Suspected Keratectasia After Klex

To evaluate the 1-year clinical efficacy and safety of high-fluence delayed intrastromal corneal crosslinking (CXL) in patients with suspected keratectasia—showing early structural instability but not meeting confirmed ectasia criteria—after KLEx (SMILE).

A single-center retrospective observational study.

We retrospectively analyzed patients showing suspected keratectasia post-KLEx. Confirmed cases were excluded. Bilateral CXL was performed even for unilateral signs, considering potential bilateral involvement. The original cap was opened, and 0.1% riboflavin was soaked for 90 seconds. Continuous UVA (45 mW/cm2, 80 seconds, total 3.6 J/cm2) was applied. We compared spherical equivalent (SE), thinnest pachymetry (TP), posterior elevation (PE), inferior-superior asymmetry (IS value), coma aberrations, and visual acuity before (T1) and 1-year post-CXL (T2).

Included were 32 eyes of 17 patients. CXL was performed 12.9 ± 9.2 months after SMILE. TP increased significantly from 481.6 ± 25.9 µm (T1) to 484.9 ± 24.5 µm (T2) (P = 0.017). Kmax slightly increased (43.34 ± 1.47 to 43.56 ± 1.46 D, P = 0.003), but PE and IS value remained stable (PE: 12.94 ± 8.59 to 12.91 ± 8.67 µm, P = 0.982; IS value: 1.67 ± 0.89 to 1.66 ± 0.92 D, P = 0.902). Visual acuities (logMAR) improved (P < 0.001). Vertical (-0.51 ± 0.29 to -0.43 ± 0.29 µm, P = 0.007) and horizontal coma (0.07 ± 0.26 to -0.01 ± 0.28 µm, P = 0.009) decreased. SE showed a mild myopic shift (P = 0.002). No severe complications occurred.

High-fluence delayed intrastromal CXL (45 mW/cm2, 80 seconds) effectively stabilized key structural indices like TP, PE, and IS value over 1 year, suppressing ectasia progression in suspected cases post-KLEx. Visual acuity improved, and specific coma aberrations decreased without severe complications. This suggests bilateral prophylactic treatment for unilateral suspects is a safe and effective early intervention.